NetClock Class

Properties   Methods   Events   Config Settings   Errors  

The NetClock class provides the current time in Greenwich Mean Time from an Internet Time Server.

Syntax

ipworks.NetClock

Remarks

The NetClock component implements a standard Time Protocol client as specified in RFC 868, as well as an SNTP (Simple Network Time Protocol).

The address of the Time Server is provided in the TimeServer property. You get the time by calling the GetTime method.

The class also allows you to synchronize your system time with that of the TimeServer. This is done through the GetAndSetTime method. Calling GetAndSetTime will request the time from the server and then set the system clock to match it.

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

Idle Property (NetClock Class)

The current status of the class.

Syntax

public boolean isIdle();

Default Value

True

Remarks

This property will be False if the component is currently busy (communicating or waiting for an answer), and True at all other times.

This property is read-only.

LocalHost Property (NetClock Class)

The name of the local host or user-assigned IP interface through which connections are initiated or accepted.

Syntax

public String getLocalHost();
public void setLocalHost(String localHost);

Default Value

""

Remarks

This property contains the name of the local host as obtained by the gethostname() system call, or if the user has assigned an IP address, the value of that address.

In multihomed hosts (machines with more than one IP interface) setting LocalHost to the IP address of an interface will make the class initiate connections (or accept in the case of server classs) only through that interface. It is recommended to provide an IP address rather than a hostname when setting this property to ensure the desired interface is used.

If the class is connected, the LocalHost property shows the IP address of the interface through which the connection is made in internet dotted format (aaa.bbb.ccc.ddd). In most cases, this is the address of the local host, except for multihomed hosts (machines with more than one IP interface).

Note: LocalHost is not persistent. You must always set it in code, and never in the property window.

LocalTime Property (NetClock Class)

This property includes the time returned by the TimeServer converted to local time.

Syntax

public String getLocalTime();

Default Value

""

Remarks

The server provides Greenwich Mean Time (GMT). This property contains the corresponding local time formatted as "MM/DD/YYYY HH:MM:SS" (where "HH" is in 24-hour format).

This property is read-only and not available at design time.

Protocol Property (NetClock Class)

This property is the protocol used by the class.

Syntax

public int getProtocol();
public void setProtocol(int protocol);

Enumerated values:
  public final static int tpTime = 0;
  public final static int tpSNTP = 1;

Default Value

1

Remarks

This property is the protocol used by the component. This property is used to specify which protocol the class will use to connect to the server. By default, this property is tpSNTP (1). The Time Protocol may be selected by setting this property to tpTimeProtocol (0).

ServerTime Property (NetClock Class)

This property includes the time returned by the TimeServer .

Syntax

public String getServerTime();

Default Value

""

Remarks

This property contains the time returned by the TimeServer. The time is given in Greenwich Mean Time (GMT) and is formatted as "MM/DD/YYYY HH:MM:SS GMT" (where "HH" is in 24-hour format).

For the corresponding local time, please consult the LocalTime property.

This property is read-only and not available at design time.

Timeout Property (NetClock Class)

The timeout for the class.

Syntax

public int getTimeout();
public void setTimeout(int timeout);

Default Value

60

Remarks

If the Timeout property is set to 0, all operations will run uninterrupted until successful completion or an error condition is encountered.

If Timeout is set to a positive value, the class will wait for the operation to complete before returning control.

The class will use DoEvents to enter an efficient wait loop during any potential waiting period, making sure that all system events are processed immediately as they arrive. This ensures that the host application does not freeze and remains responsive.

If Timeout expires, and the operation is not yet complete, the class throws an exception.

Note: By default, all timeouts are inactivity timeouts, that is, the timeout period is extended by Timeout seconds when any amount of data is successfully sent or received.

The default value for the Timeout property is 60 seconds.

TimePort Property (NetClock Class)

This property includes the User Datagram Protocol (UDP) port where the remote time server is listening.

Syntax

public int getTimePort();
public void setTimePort(int timePort);

Default Value

123

Remarks

This property is the UDP port on the TimeServer to which time requests are sent. If Protocol is set to tpTimeProtocol, the component will set this property to 37.

This property is not available at design time.

TimeServer Property (NetClock Class)

This property includes the time server from which to request the time.

Syntax

public String getTimeServer();
public void setTimeServer(String timeServer);

Default Value

"pool.ntp.org"

Remarks

This property contains the time server from which to request the time. This property should be set to a valid internet address of a time server. The server will reply with its current time (in Greenwich Mean Time).

When Protocol is set to SNTP another public server that may be used is "time.google.com".

Time requests are sent to port TimePort on the TimeServer.

Config Method (NetClock Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

DoEvents Method (NetClock Class)

This method processes events from the internal message queue.

Syntax

public void doEvents();

Remarks

When DoEvents is called, the class processes any available events. If no events are available, it waits for a preset period of time, and then returns.

GetAndSetTime Method (NetClock Class)

This method is the same as the GetTime method, but the system clock is also set to the received time.

Syntax

public void getAndSetTime();

Remarks

This method is similar to the GetTime method, but the system clock is also set to the received time (adjusted for timezone differences).

GetTime Method (NetClock Class)

This method sends a time request to the TimeServer to get the current time.

Syntax

public void getTime();

Remarks

This method sends a time request to the TimeServer on port 37. The reply is provided in the ServerTime property, and the equivalent local time is provided in the LocalTime property.

Interrupt Method (NetClock Class)

This method interrupts the current method.

Syntax

public void interrupt();

Remarks

If there is no method in progress, Interrupt simply returns, doing nothing.

Reset Method (NetClock Class)

This method resets the class.

Syntax

public void reset();

Remarks

This method will reset the class's properties to their default values.

Error Event (NetClock Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultNetClockEventListener implements NetClockEventListener {
  ...
  public void error(NetClockErrorEvent e) {}
  ...
}

public class NetClockErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Config Settings (NetClock Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

UDP Config Settings

Socket Config Settings

Base Config Settings

Trappable Errors (NetClock Class)

NetClock Errors

UDP Errors

SSL Errors

TCP/IP Errors